Medium weight organic very high quality. Hypoallergenic, made in USA. Keep them from climbing out of the crib! https://castleware.com/collections/sleeper-bags-wearable-blankets/products/long-sleeve-fleece-sleeper-bag?variant=43479920771319 Not a polyester micro fleece, this is the real deal. All natural, cotton fleece that allows for the body to breathe while retaining heat. Better for baby and the environment. Sturdy YKK zipper unzips from the bottom up for easy diaper access. Zipper is backed with a fabric placket for comfort and protection. One way zipper pull ensures that baby cannot undress themselves during the night. 100% GOTS certified organic cotton fabric. Preshrunk in hot water only, prior to cutting and sewing. Not treated with any chemical finishes. Sustainably sourced and ethically produced with love in the USA. About Fleece: A dense yet lightweight fabric that is soft and cuddly. Kids love this fabric because the fuzzy side is on the inside. Reduces the likelihood of rashes and eczema outbreaks. GOTS certified organic cotton fabric: Our fabrics are made exclusively for us in Los Angeles and South Carolina from GOTS certified organic cotton fiber. Standard 100 by Oeko-Tex(R): Qualifies for Standard 100 by Oeko-Tex(R). Fabric is dyed with low impact, fiber-reactive dyes. Cleaner for the environment and your child. Natural is dye free.